The moment a massive brawl erupted on the sidelines of a world-famous bareback horse race in the medieval town of Siena, Italy, has been captured on camera. The fist-fight, involving dozens of people from rival contrade, or parishes, happened under the puzzled eyes of thousands of spectators who had gathered in town's main square, Piazza del Campo, for the traditional Palio di Siena.

In the clip recorded earlier this week, two gangs are seen slowly moving towards each other at the end of the race, before eventually coming into contact, triggering short-lived clashes. The opposing factions were said to be members of the Onda and Torre, two of the 17 contrade, each representing a town district, that enter a horse and a rider in the race. The fight was quelled by police, although no arrests seem to have been made, La Nazione newspaper reported.

The Palio di Siena is entrenched in the Tuscan city's proud tradition, having been held regularly twice a year since the mid-1600s, and tensions between the rival contrade, each representing a district, are not a novelty. Disputes may arise because of the race result or due to some districts' decades-long bitter enmity.

As the Onda and Torre were fighiting, at the other end of the square members of the Nicchio and Valdimontone clans were reportedly scuffling. The two contrade had been involved in a brawl also at the previous Palio, in July, sparked by a dirty race move by the Valdimontone jockey who literally threw his rival off the horse.

The parishes all have their own banners, jockeys' colours and mascots, dating back to the Middle Ages and the race's winner is determined by which horse -- not which rider -- crosses the finish line first. The last edition was won by the Selva.

The Cencio or Palio (the banner that is awarded to the winning parish) is carried during a parade before the Palio of Siena horse raceReuters